Device for the cyclic rearrangement of a pile of sheets

ABSTRACT

A device for the cyclic rearrangement of a pile of sheets with a housing having a viewing window, from which housing a slider member can be withdrawn and reinserted, and with elements for removing a sheet from an inserted pile and transferring the same to the other end of the pile on each movement cycle of the slider member. When the slider member is inserted the pile is pressed against the viewing window by a pressing arrangement which comprises rails supported on leaf springs. The rails have integrally moulded function elements, such as anchoring projections, sheet stop members, blocking projections, spacer ribs and guide prongs.

The invention relates to a device for the cyclic rearrangement of a pileof substantially rectangular sheets of nominally identical thickness.

Such a device, which here and hereinafter shall be referred to as a"sheet-changer" for short, is described and illustrated in publicationsWO 86/03019, WO 86/03018, WO 86/03022, WP 86/03026, WO 86/03028, WO86/03029, WO 86,03030, which are hereby incorporated by reference intheir entirety.

The known device comprises a housing provided with a viewing window andforming the first frame part, and a slider member forming the secondframe part. The separating elements are formed on the one hand by a stepwhich is arranged fixedly in the housing, and on the other hand by aninner transverse member of the slider member called the separator. Thefeeding means comprises free ends of hook-like construction of springsmounted in the housing, which engage the edges of the sheet lyingfurthest away from the step. The individual sheet is held in the housingin that in the housing there are fixedly arranged retentive coatingsextending in the direction of movement of the slider member, againstwhich retentive coatings the individual sheet is pressed by smallrollers mounted on the separator. The separator also serves as aretaining means for holding the remainder of the pile in the slidermember. The guide means comprises the free ends of spring arms mountedin the housing that lift the individual sheet away from the retentivecoatings when the slider member is pulled and guide it in front of areturn slot defined by the separator. The pressing device too is formedby the free ends of spring arms mounted in the housing, namely by a pairof springs of the feeding means and a pair of spring arms forming theguide means. The spring arms are respectively controlled, released anddepressed by these springs for given portions of the relative movementof the slider member.

With the slider member inserted, the pile rests on ledges of the slidermember parallel with the viewing window, the ledges defining a levelwhich is closer to the viewing window than that of the retentivecoatings so that the pile is spaced from the retentive coatings onreinsertion of the slider member. Furthermore, the separator is designedsuch that, as the slider member is withdrawn, it is not possible for oneor more sheets to be separated from the remainder of the pile inaddition to the separated individual sheet. Reference should be made tothe content of the said publications for further details.

The known picture changer gives no cause for complaint as regards itsfunction. However, it is in need of improvement in two areas:

Firstly, a large number of functional elements are provided, which haveto be manufactured separately and the correct co-operation of whichcannot be determined until they are assembled. Secondly, the control ofthe spring functions by the slider member causes variable frictionconditions over the withdrawal path, which the user is able to feelclearly.

It is the aim of the invention to develop a sheet changer whosemanufacture is simplified and at the same time the relative movement ofthe frame parts can take place with essentially the same or at leastvery gradually variable and minimal friction over the withdrawal path.

This problem is solved by the invention described below.

This concept offers a whole series of advantages:

Whereas in the known sheet changer the control of the spring functionsis effected by the slider member running onto these springs, in theconstruction according to the invention the rail elements can beanchored by or released at one end at fixed housing parts. The railelements may furthermore have integrally moulded elements whichco-operate with the separator to prevent the separation of a secondsheet from the remainder of the pile. Projections, which serve asfeeding means, may also be integrally moulded with the rails. Theretentive coatings can be arranged on the rails, as can the means forholding the remainder of the pile away from the retentive coatings asthe slider member is reinserted. Other functional elements can beprovided on the rails, for example the blocking elements which preventthe sheets getting beneath the pressing system as a pile of sheets inplaced in the sheet changer The rails may also be provided with adifferent controllable transporter for the individual sheet.

Further features and advantages of the invention will become apparentfrom the subsidiary claims and from the description of exemplaryembodiments.

Exemplary embodiments of the invention are explained in detail belowwith reference to the accompanying drawings.

FIG. 1 shows in perspective view a sprung rail and components of thehousing co-operating with it,

FIG. 2 shows diagrammatically a cross-section in the region of the railin co-operation with the separator shoe,

FIG. 3 is a longitudinal section through the separator shoe,

FIG. 3a shows the shoe in perspective,

FIG. 4 is a section at right angles to the direction of movement of theslider member across the width of the slider member,

FIG. 5 shows the conditions during insertion of the slider member,analogously to FIG. 2,

FIG. 6 shows the positions of the parts level with the separator shoe oninsertion, analogously to FIG. 5,

FIG. 7 shows in a diagrammatic side view the position of the shoe andthe rail with only a few sheets in the changer,

FIG. 8 is a diagrammatic longitudinal section of the relative positionof the parts when the slider member is inserted,

FIG. 9 shows the start of the withdrawal,

FIG. 10 shows a somewhat later phase,

FIG. 11 shows in detail, in a diagrammatic longitudinal section, theinitial phase of the rearranging process with the separator and railsco-operating,

FIG. 12 shows a next phase in analogous view,

FIG. 13 shows a later phase,

FIG. 14 shows a subsequent phase,

FIG. 15 shows the next phase,

FIG. 16 shows, analogously to the preceding Figures, the relativeposition of the parts when the slider member is pulled out,

FIG. 17 shows in detail the end position of the separator relative tothe rails,

FIGS. 18 to 20 correspond to FIGS. 8 and 16 and 15 respectively, in analternative configuration of the rails,

FIG. 21 shows the front end of a rail from FIGS. 18 to 20,

FIG. 22 is a longitudinal section through the closed changer toillustrate the housing construction,

FIG. 23 is a partial section at right angles to the section plane ofFIG. 22 on an enlarged scale compared to the latter,

FIGS. 24 to 29 show the behaviour of the auxiliary springs in differentphases and modes of operation of the changer,

FIGS. 30 and 31 show in two different phases the mode of operation of analternative form of the retaining means for the individual sheet,

FIGS. 32 to 34 show diagrammatically a further construction forretaining an individual sheet,

FIGS. 35 to 37 show in partial section under two planes at right anglesto one another the releasing device for removal of the entire pile,

FIGS. 38 and 39 show in diagrammatic longitudinal section the mode ofoperation of this element,

FIG. 40 shows a perspective view of a changer, and the operation of thechanger in general will now be explained with reference to this Figure.

FIGS. 41a, b illustrate a problem that occurs with bowed sheets,

FIGS. 41c and 42 show a form of rail for eliminating this problem,

FIGS. 43 to 46 show four phases of the commencing changeover process atthe other end of the rails of the modified form of embodiment,

FIG. 47 shows in a perspective partial view the modified rail anchoringsystem,

FIG. 48 shows in a diagrammatic vertical sectional view the position ofthe co-operating parts with the frame parts pushed together,

FIG. 49 shows in an analogous view the situation with the frame partspulled partly apart,

FIG. 50 shows in partial perspective view the elements for disabling thechange-over process,

FIG. 50a shows the co-operation of rails, separator and slider member inpartial perspective view,

FIG. 51 shows in perspective view the bent wire part which is insertedinto the rails shown in FIG. 50,

FIG. 52 illustrates the assembly of the bent wire parts,

FIG. 53 shows on a very enlarged scale the mode of operation of thedisabling member,

FIG. 54 shows in cross-section through the rails the position andmounting of the wire member,

FIGS. 55 to 58 show four phases of the disabling of the system,

FIG. 59 shows, in a plan view onto the bottom side of the housing, thearrangement of the disabling system,

FIG. 60 is a section on a level with the line 60--60 from FIG. 59,

FIG. 61A to 61C show details of the disabling system in operation,

FIG. 62 shows an enlarged view of another modified embodiment in partialvertical section,

FIGS. 63 and 64 show the procedure at the start of withdrawal of theslider member,

FIG. 65 shows analogously to FIG. 62 a further form of embodiment, and

FIG. 66 shows yet a further alternative in an analogous illustration.

The changer shown in FIG. 40 is similar to a conventional picture framefor hanging up or standing up. It comprises a housing 100 which on itstop side (where the terms "top" and "bottom" are used in the followingdescription, they refer always to the position in relation to thehousing, regardless of how this itself is arranged in the room) has aviewing window 102 in the form of a transparent pane 102. Parallel withthe plane thereof, a slider member 104 can be withdrawn from andinserted into the housing, and on each complete backward and forwardmovement of the slider member a sheet change is effected in normaloperation, that is to say, a pile of sheets, for example photographs,accommodated in the changer is cyclically rearranged in such a mannerthat, as the slider member is withdrawn, the lowermost sheet of the pileis held firmly in the housing, whilst the slider member carries theremainder of the pile with it out of the housing; as the slider memberis reinserted, the picture is deposited on top of the remainder of thepile. Inside the housing there is an arrangement for exerting pressureon the pile which presses the pile upwards when the slider member isinserted and which is pressed downwards as the slider member iswithdrawn. This is effected by means of a rear and inner transversemember of the slider member, which, because it separates the individualsheet from the remainder of the pile, is called a "separator"; theslider member comprises furthermore two parallel lateral bars 106 ofL-shaped cross-section, and a front assembly 108; since the slidermember is open underneath, the pressing arrangement secured in thehousing is able to act on the sheets carried by the lateral bars of theslider member.

FIG. 1 shows the base plate 110 of the changer housing, the countersunkgroove 111 serving to accommodate a stand, such that it can be let inflush and folded out, for positioning the changer in the manner of astand-up frame. A pile of sheets (not shown) is pressed by a pressingarrangement towards the viewing window 102 provided in the housing foras long as the slider member 104 is inserted fully into the housing.

The pressing arrangement comprises two rails 112 parallel with oneanother and with the direction of movement of the slider member 104,each of the rails being fastened to an associated leaf spring 114. Forthis purpose the rail, which is injection-moulded from plasticsmaterial, has a rivet projection 116 which, on assembly, is pushedthrough a corresponding opening in the metal leaf spring and is expandedby deformation behind this. One end of the leaf spring 114 is placed ona locating peg 118 on the base 110 of the changer housing, while theother, free end of the leaf spring, although it is supported laterallyby the walls of a groove 120 in the housing base, is able to move in thelongitudinal direction of the rail (here and elsewhere, "longitudinally"means "in the direction of the slider member movement"; "transversely"means at right angles to the longitudinal direction). The leaf spring isformed into an upwardly arched bow, and the rail 112 is fastenedapproximately in the middle thereof. As the two rails and the associatedsprings and housing parts are of mirror-symmetrical constructionrelative to the centre line plane of the changer, only one half of thepressing arrangement needs to be explained in detail.

On withdrawal of the slider member 104, the separator 122 thereof runsonto the two outer prongs 124 at the inner end of the rail 112 ("inner"means "furthest away from the slider member front", "outer" means "closeto the housing opening through which the slider member moves"), andpresses it downwards against the force of the leaf spring 114. As thishappens, the pile of sheets (FIG. 10) supported by the rails 124 alsomoves away from the viewing window 102 and the separator carries thepile outwards, with the exception of the lowermost sheet which is heldfirmly on the rails. The following steps are taken for this purpose:

Close to its outer end, the rail has integrally moulded upstandingprojections 126 from which the lowermost sheets of the pile derivesupport, so that they are checked in relation to the separator movement.Close to the inner end of the rail, moulded integrally with the housingbase 110 on either side of the prongs 124 there are upright, narrowrails 128, which have a support face 130 parallel with the housing baseand parallel therewith a blocking face 132, the two faces beingseparated from one another by a step 134. As soon as the rails 112 havebeen pressed down by the separator, the inner edge of the lowermostsheet of the pile positions itself on the support faces 130. The step134 has a height which is greater than the thickness of a single sheetbut less than the thickness of two sheets, so that this edge of thelowermost sheet lies protected behind the step and the separator passesover it. The next lowest sheet on the other hand is carried by theseparator and slides off the projections 126. On the side of theseparator facing the rails there are mounted spring-loaded shoes 136with small rollers 138, as will be explained hereinafter in detail. Thesmall rollers have a width which is approximately the same as that of aretentive covering strip 140 arranged centrally on each rail.

The retentive covering is so called because it consists of a materialwhich has a distinctly greater friction coefficient with the material ofthe sheets to be changed than this latter material has with itself (thatis to say, the friction between the lowermost sheet and the retentivecovering is much greater than the friction between the lowermost sheetand sheet immediately adjacent to it in the pile). The retentivecovering may consist merely of a roughened area on the rail material, oralternatively of a special coating of an elastomer or a similarmaterial. The force of the spring 114 acting from below presses thelowermost sheet with the retentive covering towards the associated smallroller, so that the sheet is held firmly gripped.

The rail cross-section shown in FIG. 2 reveals the action of two lateralupright ribs 142: the top side of the retentive covering lies recessedwith respect to the plane which is defined by the ribs and in which theindividual sheet lies, and the small roller distorts the sheet, as shown(exaggeratedly) in FIG. 2. This is important for the return travel ofthe slider member, during which the individual sheet is located at thetop close to the viewing window and the remainder of the pile is beingtransported inwards along the rails into the housing again: the smallrollers of the separator then run in front onto the retentive coverings(FIG. 6), while the sheet that is then lowermost in the remainder of thepile is held by means of the ribs 142 away from the retentive coverings140, so that these ensure the unchecked insertion of the remainder ofthe pile (FIG. 5).

FIG. 6 shows that the small roller 138 is narrower than the shoe 136which in its turn, when the slider member is fully inserted, is wideenough to position itself, between the prongs 124 and on both sides ofthe central tongue 144 of the rail on which the retentive covering ends,on the blocking faces 132, and to lie on these under spring force whenthe slider member is pulled. The shoe on the one hand and the supportfaces on the other hand thus define a through-slot for the individualsheet, and the slot height is determined by the step 134. Only when therelevant edge of the individual sheet projects into the through-slotdoes the small roller run gently onto the inclined run-on edge 146 atthe free end of the tongue 144; more accurately, this tongue positionsitself gently from below against the small roller because the rail end,as a result of the separator 122 on both sides of the shoe meeting thethickened ends 146 of the prongs 124, had pressed the rail down "toofar".

As FIGS. 3 and 3a show, the shoe 136, together with the small roller,which preferably consists of metal, forms an assembly which is movablyguided in the separator. Between a transverse member 137 of the shoe anda support 139 integrally moulded with the separator there is inserted ahelical compression spring 131. On each side of the spring the separatorhas projections 133 with a right-angled bend which engage beneath a topface 129 of the shoe and by means of a snapped-in lug prevent the shoefrom falling out; the shoe, however, can be displaced against the springbias for a limited distance in a direction approximately parallel to theinclined run-on face 148 of the separator. The small roller 138 isinstalled from below into the bearing blocks 143 of the shoe and issafeguarded against falling out in a manner not illustrated. Thesesafeguarding means are not necessary for operation, but simplifyassembly. The edge 145 of the shoe running in front of the small rolleras the slider member is withdrawn is set back with respect to the smallroller to such an extent that it is not able to touch the individualsheet even when there are only a few sheets in the changer and the railsare therefore inclined steeply towards the plane of the viewing window(FIG. 7).

FIGS. 8 to 10 show in a diagrammatic side view the steps in the initialphase of the sheet change-over, while FIGS. 11 to 15 show parts of thisin detail.

Stationary phase: FIG. 8. The shoes 136 are not yet resting on theblocking faces 132, but are supported by means of stops on theseparator, since the blocking faces 132 at their end remote from thesteps 134 likewise have a step 150. This is angled so that the shoe isable to slide on, in the same way as the step 134 and the support face130 have run-on slopes which co-operate with a corresponding slope 152of the shoe. The dimensions are such that when the slider member isfully inserted the shoe comes to rest exactly behind the slope of thestep 150, so that the changer is not able to open on its own butrequires a certain, even if only slight, pulling force to be exerted onthe slider member.

The top edge 154 of the separator lies immediately in front of thethickened portions of the prongs 124, but the rails are still able tomove freely under the action of the springs 114 towards the window orpress an inserted pile against this.

Preparatory phase FIGS. 9 and 11. The slider member is withdrawn by afew millimetres. The inclined face 148 of the separator 122 has run ontothe prongs 124 and has pushed these downwards a little way. The leafspring 114 is extended somewhat by this and since it is fixed at itsouter end to the housing base, its inner end travels counter to thewithdrawal direction of the slider member, and the rails too aredisplaced relative to their starting position.

Separating phase: FIG. 12. The edge of the shoe 136 running in front ofthe small roller passes over the end transverse edge of the lowermostsheet of the pile facing towards it.

Start of the retaining phase: FIG. 13. The shoes have passed over thesupport face, and the small rollers 138 have positioned themselves onthe inclined face 146; the separator pushes away the remainder of thepile in front of it. As clearly shown in FIG. 10, the leaf springs 114have been even further extended, and the rails have been displaced stillfurther in an inward direction.

Retaining phase: FIGS. 14 and 15. The separator approaches even closerto the connection point between rail and leaf spring. The leaf spring isalmost fully extended and the inclined face 146 of the inner middletongue of the rail projects beneath hooks 156 which are integrallymoulded internally on the rails 128. Without these hooks the inner endof the rails 112 would rise again under the action of the leaf springs114 as soon as the separator has been moved out beyond a pivot pointclose to the rail centre; but the rails remain depressed until theslider member has reached its outer end position and also during theinward path of the slider member until the other side of the pivot pointof its stroke.

The situation shortly before the outer end position of the slider memberis illustrated in FIGS. 16 and 17. The Figures show that the smallrollers 138 have already passed over the outer transverse edge of theindividual sheet 160 so that this is no longer held gripped but liesbeneath the inner end of the shoe 136. Close to their outer end, therails 112 have a downwardly angled protection 164 which reaches close tothe housing base 110, but does not touch this (as otherwise the railwould jam between the separator and the base). This projection preventsthe leading edge of a sheet from getting beneath the rails as the deviceis filled with sheets.

Shortly before the outer end of the rails 112, their retentive covering140 also terminates. The end of the retentive covering is cut off at anangle and in front of this the rail has a raised portion 166 terminatingin a corresponding angle, the height of the raised portion not beingconstant, however, but decreasing from one longitudinal side to theother. In this manner it is possible to ensure that the small rollerrolls on and off the retentive covering without being checked by this,although it has noticeable thickness tolerances.

FIGS. 18 to 21 show an alternative configuration of the rails. Insteadof the integrally and rigidly moulded-on projections 164, in this case amovable projection 170 is connected by way of a so-called film hinge 172to the rail body and is guided by means of a straight guideway 174 onthe housing base. FIG. 20 shows the situation in which the slider memberis but incompletely withdrawn, so that the resilient rails still projectwith their outer ends; if an attempt is now made to insert sheets, theprotection reliably prevents sheets being able to get beneath the therails. In this case, the rail would be made from a suitable plasticsmaterial, with the film hinge being capable of withstanding continuousalternating stress, for example polypropylene.

FIGS. 22 and 23 reveal clearly the construction and arrangement of theauxiliary springs 162 and 163. These are relatively weak leaf springswhich are fastened at one end to the housing base, namely beneath theslider member lateral bars 106 so that when the slider member isinserted they are depressed. If the slider member is pulled (FIGS. 24 to27), the inner auxiliary spring 162 first of all lifts the inner endedge of the individual sheet in front of a stop 175, and when the slidermember is fully pulled out the leading edge of the individual sheet isalso lifted, so that it lies in front of the top side of the separator122 and is able to pass through the gap between this and the top side ofthe housing when the slider member is pushed back.

As long as the changer is filled with sheets, as the slider membertravel commences the separator runs onto the lowermost sheet and thispresses the auxiliary springs lying laterally next to the rails with itbeneath the separator. If the changer has not been filled, the auxiliarysprings project freely upwards. So that in this case they cannevertheless be pressed down by the separator, this has correspondingrecesses 177 with a wedge-like angled part which is sufficient to allowthe free spring ends to slide down, as indicated in FIGS. 28 and 29.

FIGS. 30 and 31 show an alternative method of holding the individualsheet on the rails 112. On the underside of the rails there isintegrally formed a slideway 180 in which a sheet metal gripper 182 isinserted such that it can be displaced to a limited extent in thedirection of the slider member movement. In the starting phase (FIG.30), the separator 122 runs first of all onto an upwardly directedspring hook 184 of the gripper and carries this for a limited distancewith it, until the angled stop portion 186 meets the rear end of therail. As this happens, the gripper is pushed with its spring hook endover the inner transverse edge of the sheet and holds this firmly. Thespring hook yields resiliently outwards on further travel of the slidermember. Close to the outer end position of the slider member, theseparator passes over an outer spring hook of the gripper. As the slidermember is pushed back, the separator presses the gripper into itsstarting position again in that it runs onto this outer spring hook 188until the gripper strikes the front rail end. The sheet is now releasedand can be lifted by the auxiliary springs 162. On further insertion ofthe slider member the spring hook 188 yields inwards (shown by a brokenline) and the same applies to the inner spring hook 184.

FIGS. 32 to 34 illustrate another alternative for retaining theindividual sheet. Close to the outer end of the rail 112, a pivotableangled member 190 is mounted thereon such that it pivots about a pivotpoint 192. Starting from the stationary position (FIG. 32), first of allthe individual sheet 160 is checked at the projections 126, while theremainder of the pile runs over the inwardly directed arm of thepivotable angled member, which arm tapers to an edge like a knife bladeand, after the slider member has travelled a short distance, meets theupright second arm of the pivotable angled member. The pivotable angledmember is deflected thereby but the blade-like arm is unable to lift theremainder cf the pile, so that it is resiliently deformed. Theindividual sheet is now also pushed over the projections 126 (FIG. 34)until its outer transverse edge meets the stop projection 194 of thepivotable angled member. The tapered extension arm is thereby heldpressed over the transverse edge for as long as the remainder of thepile is being moved. When the separator also has passed over theprotection 194, the pivotable angled arm is able to spring up andrelease the individual sheet. During the return travel, the pivotableangled member is displaced back into its starting position again.

FIGS. 35 to 39 illustrate the means serving to disengage the change-overfunction, s that when the slider member is pulled the entire pile istransported by the slider member out of the housing. These meanscomprise a frame 200, the longitudinal struts 202 of which are displacedfrom below into recesses 204 on the underside of the separator 122 andin so doing lift the sheet edges lying in front of the separator to suchan extent (FIG. 38) that the lowermost sheet is unable to get into thethrough-slot beneath the shoe 136; this sheet also is therefore carriedalong by the slider member (FIG. 39). The frame rests on a button 206,which in turn is fixed by way of a plastics spring 208 on the housingbase 110 and can be displaced manually through an aperture 210 in thehousing base.

The rest position of the button, in which the change-over function is"switched on", is illustrated in FIG. 35. If the button is pressed, thenunder the compression of the spring 208 it snaps over the locking edge212 of the housing aperture 210 into the position shown in FIG. 37, inwhich the frame 200 blocks the change-over. If, as the slider member iswithdrawn, the separator now runs onto the transverse strut 214 of theof the frame 200, this and with it the button 206, is tilted, so thatthe button is able to snap back into its initial position again, thetilting motion being effected about a stop 216. The spring 208 issecured to a base 218, which protrudes from the housing base 110, and isguided against a rib 220 so that the frame assumes the position parallelto the housing base shown in FIG. 37 even when the button is depressed.

FIGS. 41a, b, c and 42 show the end of a rail of an alternativeembodiment. It is desirable to retain the individual sheet in thehousing with a maximal force and the best engagement is provided by a"hook" lying adjacent the sheet edge, which hook extends approximatelyat right angles to the sheet plane. The hook, however, must not exceed aheight equal to the thickness of one sheet, in the case of photographicprints for example about 0.25 mm, so that the second lowermost sheet andall the following ones are able to pass over it. As long as all sheetsare perfectly plane, such a system would function. But this is notalways the case, however, because, for example, photographic prints bowdepending on the atmospheric humidity, for example about a transverseaxis; in this case such a short hook is unable to grip the lowermostsheet (FIG. 4la). The pressure exerted by the springs 306 on the rail isnot sufficient to flatten the sheets lying thereupon and thus bring thehook into engagement with the lowermost sheet. For this reason a railprofile according to FIG. 41b is preferred. FIG. 41c shows the rail endon an enlarged scale, and FIG. 42 illustrates a functional detail. Thetwin hook 300 extends upwards at right angles from a short plateau 301.It forms the end of a sloping ramp 302 which starts from the plane upperside 303 of the rail. The supported concavely bowed sheet follows theramp and is engaged by the hook. If by chance the sheet to be separatedis somewhat shorter than the sheet immediately following it, it iscarried by the separator shoe in the direction towards the hook andthrows off the sheet lying above it even when this is convex (FIG. 42);as it does so its leading edge slides along the plateau 301. Thisplateau also prevents the leading edge of the second lowermost sheetfrom being temporarily engaged and damaged by the hook if the railassumes an extremely oblique position owing to the fact that there areonly a few sheets in the changer.

The retentive coating 140 also has a sloping ramp 305 parallel to theramp 302 so that the sheet to be separated is not too badly deformed bythe small roller between the two ramps 302.

FIGS. 43 to 46 show the other end of one of the rails shown in FIG. 41,42 co-operating with the separator 400, the shoe 402 thereof, the smallroller 404 and the support 406 and the blocking face 408. As in thefirst embodiment, the rail has a three-pronged end, but the contour ofthe prongs is of somewhat different design.

FIG. 43 shows how, after the start of the slider member withdrawal, theinclined face 410 of the separator has run onto the thickened prongs 412of the rail. Between FIGS. 43 and 46 the inclined position of the railvaries between, for example, 5° and, for example, 7°. FIG. 44 shows howthe separator follows with a rounded-off portion 414 the upper curvatureof the prongs 412. After the portion 414 has passed over the prongs, theupper curvature of the prongs 412 lies against the plane face 416 of theseparator, which face now rides on the outer prongs of the rail. In sodoing, the shoe 402 approaches with its small roller 404 the middleprong 418 of the rail, so that the small roller is able to run on therounded control face 420 thereof. On further travel of the slidermember, the rail is finally pressed down into its lowermost position,shown in FIG. 46.

In FIG. 46, two sheets 422, 424 are illustrated. The sheet 422 isintended to remain in the housing, while the sheet 424 is to betransported by the separator, or the shoe 402 thereof. It will be seenthat the shoe has a transporter edge 426 which extends at a steeperangle than the inclined face 410. The sheet 422 is positioned on thesupport 406 and cannot be engaged by the transporter edge since it isheld by the sheet 424 behind the step that separates the support face406 from the blocking face 408. It is essential that the rail "dips"sufficiently far so that the sheet edges are not prevented from beingpositioned on the support 406.

The perspective illustration of FIG. 47 clearly illustrates the shape ofthe prongs. On both sides of the control face 420 there is a free space428 for safety reasons. Although the small roller 404 has an axialdimension that is the same as the width of the central prong 418, theslider member necessarily has some free play in the housing, sincewithout those free spaces the shoe 402 could strike with its edge 426against the control face before the small roller presses the rail away;this can be seen clearly in FIG. 45.

It was explained above that this end of the rail is anchored, such thatis performs a rocking movement, beneath immovably integrally mouldedhooks when the slider member has passed over the pivot point of the leafspring/rail system. Such a construction, however, is very demanding asregards the accuracy of manufacture and assembly because, when the sheetchanger is completely filled, the remaining rail travel between thefreely movable rail, when the slider member is inserted, and theanchoring position, when the slider member is withdrawn, is onlyextremely small, for example a few tenths of a millimetre.

It is therefore preferred to design the hook so that it is not immovablebut movable, so that, controlled by the slider member movement, it isable to assume a holding position on top of the rail, or a releaseposition. It is desirable for the hook not to reach its engagingposition until after the rail has been depressed so that the latter willengage the hook from beneath.

This is achieved by the construction illustrated in FIGS. 47, 48 and 49.It should be noted that in FIG. 47 the rail and the engagement systemare drawn in an exploded view; the actual position of the parts is shownin FIGS. 48 and 49, respectively.

Between the ribs 430 having the support and the blocking faces, there isarranged a spring-biassed anchoring bracket 432. This is a punched andbent component of resilient sheet metal having a first window 434, thetransverse member 436 of which pivots over the extension 438 of the railas soon as the free control projection 440 has been released by theseparator (or more accurately by the small roller thereof).

The control extension has a second window 442, so that when the slidermember is inserted the extension does not rest on the central rib 444which is integrally formed with the housing base 446. The central ribhas two functions. Firstly, the anchoring bracket 432 is anchored bysnap-fitting to the end edge 448; the retaining bracket is guidedbeneath a pin 450 which extends transversely to the direction ofmovement of the slider member. The second function of the central rib444 consists in forming a guide ramp 452 for the small roller 404. Whenthe slider member is inserted, both the small roller and the shoe shouldbe subjected to only slight spring bias. During the change-overoperation, however, the shoe, which is engaged by the separator via aspring, is pressed with fairly strong bias against the blocking face408. For this reason the blocking face 408 is recessed at 454, so thatthe shoe does not engage it. At the start of the slider member movement,the small roller runs first of all onto the ramp 452 and lifts the shoehigher than the level of the blocking face 408, onto which the shoe isthen lowered as soon as the small roller comes clear of the middle rib.

The user should be able to disable the change-over function so that theentire pile can be transported out of the housing by the slider member.accordingly, means are required which

lift the end of the lowermost sheet of the pile away from the support sothat it can be engaged by the shoe, and

release the other end edge of the same sheet from the hooks 300.

These means are illustrated in FIGS. 48 to 61.

The housing base 446 has an aperture 460 with integrally moulded guidingrails 462, between which a key 464 is snap-fitted. The key isdisplaceable by a limited distance in the direction of the slider membermovement, thereby carrying with it an integrally moulded transversemember 466 which in its turn displaces a pair of wedge-shaped ribs 468.These extend next to the inner ribs 430 and parallel therewith and, asshown in FIG. 55, each wedge-shaped rib 468 has a horizontal upper edge470 on the same level as the blocking face 408. On displacement of thekey 464 in the direction of the housing opening, the edge 470 assumesthe position shown in FIG. 55, and it will be seen that the lowermostsheet cannot be positioned on the support 406 but has to be taken awayby the shoe. The wedge-shaped ribs furthermore have a control edge 472which here extends at an angle of, for example, 45°. Its function willbe explained later.

FIG. 50a shows the co-operation of the separator, the shoes connected toit, the small roller located in these, and the rails. In particular, tothe foot part 411 of the slider member side rail there is fastened alifting spring 413 which lifts the separated individual sheet in frontof a return slot during the return stroke of the separator.

The displacement of the other sheet end from its position in front ofthe hooks 300 necessitates a modification of the rails, the position ofthe rails not being predictable when the slider member is insertedbecause this position depends upon the number of sheets that arecontained in the device. Provision is therefore made for such amodification of the rails to be effected when the rail, after the startof the slider member withdrawal, follows a path which is forced upon itby the separator regardless of the number of sheets.

Each rail carries a control member 474 which is bent from a single pieceof wire. The two free ends of the wire member are provided with eyelets476 that co-operate with a control ramp 478 of the rail. A displacementof the eyelets to the left in FIG. 53 results in a sheet, which wouldotherwise assume a position in front of the hooks 300, being guided overthe latter, so that the hooks remain ineffective. At the same time, thespring is biassed (or an existing bias is increased) so that the eyelets476 tend to return to their withdrawn position, illustrated in FIG. 53by a solid line, and which is defined by the stop 480.

The other end 482 of the control member is guided and bent at rightangles beneath the middle prong 418 of the rail. When the separatordepresses the inner rail end, this transversely extending wire portionstrikes against the control edge 472 of the wedge-shaped rib. Thecontrol member is therefore shifted ever further to the left withcontinuing depression of the rail end, with the eyelets being displacedcorrespondingly. FIG. 58 shows that this displacement has already beenconcluded before the transporter edge of the shoe meets the transverseedge of the lowermost sheet of the pile. A transverse rib 484 mouldedintegrally with the rail body spaces the leaf spring 486, by which therail is carried, from the control member end 482, so that the lattercannot be clamped by the spring 486 and remains freely movable, evenwhen the rail has been fully depressed.

The control member is mounted on the rail by a snap-fit method. The railhas two parallel grooves 488 in which the longitudinal portions of themember are freely displaceable. At one point over each of these groovesthere extends a claw 490 around which the free ends of the controlmember are bent and behind which they assume their extended linear shapeagain. A widened portion 492 of the groove enables the wire to bedeformed simply by pressing on it and to be mounted by means of asnap-fit there and then.

There are additionally provided means that prevent incorrect operation,that is to say, an actuation of the key 464 with the slider memberpartly withdrawn, and that ensure that the key and all componentsconnected therewith are returned automatically to their initialposition. These means are illustrated in FIGS. 60 to 61C, FIG. 60 beinga cross-section level with the key 464 and FIGS. 61B and C being partialsections taken at right angles thereto.

The transverse member 466 comprises an upper bar 467, which is able toyield in the direction of the key 464, and a guiding bar 469 lyingtherebeneath which is connected to the key and, by way of thewedge-shaped ribs 468, to the upper bar. From the latter there extendinwards, that is, in the opposite direction to that of the wedge-shapedribs, a central arm 471 with a hole 473, and also downwards two controlpins 475. A reset tongue 477 with which is associated a reset projection497 integrally moulded with the housing base extends backwards from thekey 464.

FIG. 61A shows the initial position with the slider member pushed in. Itwill be seen that the separator has on its underside a recess 479terminating in a control ramp 481; a cam projection 483 integrallymoulded with the upper bar 467 projects into this recess. If, startingfrom this position, the key is displaced to the left in FIG. 61B todisable the change-over function, the cam projection 483 is presseddownwards by the control ramp 481, taking the central portion of theupper bar 467 downwards with it. The hole 473 of the locking arm 471comes free of a locking pin 485 moulded rigidly on the housing, and thecontrol pins 475 too are able to yield resiliently downwards intocorresponding recesses in the housing base. The reset tongue yieldsresiliently as it passes over the reset projection. Even if the slidermember is only partly withdrawn, the key remains latched. The separatoris able to run over the actuated key to deform the upper bar again,since even in this position of the key there are recesses in the housingbase lying opposite the control pins. (FIG. 61C). As the slider memberis returned, it displaces the key initially for a short distance towhere the control pins are locked so that the bar 467 is unable to yieldresiliently; instead, the entire assembly of the key is returned to theinitial position as a result of the reset tongue being deflected by therest projection.

FIGS. 62 to 64 show a modified form of embodiment of the piletransporting elements particularly suitable for co-operation with thehook-like transporter 300 for the individual sheet. As thesetransporters engage virtually at right angles to the sheet plane, theseparating force is maximal. However, this is only effective if thesecond sheet to be separated from the individual sheet is engaged anddisplaced with at least approximately the same maximal force. That is tosay, the end face of the shoe engaging the second lowermost sheet shouldextend also at right angles to the sheet plane.

In the constructions described so far, this face is inclined for thereason that the pressure exerted on the pile edges by the separator isto be converted into a downwards movement of the rails carrying thesheets, so that the last (lowermost) sheet to be separated is reliablypositioned on the support and in front of the blocking face.

In order to permit such an advantageous configuration of the transporterface of the shoe, the construction according to FIGS. 62 to 64 isselected.

The shoe 502 has an inclined face 504 along which, as in the previousforms of embodiment, the sheet edges are conveyed to the support 506.The second lowermost sheet 508 is provided with a separate transporterface 510 extending at right angles to the support plane, the height ofwhich transporter face is clearly less than the thickness of one sheetso that at the start of the withdrawal movement the entire pile,including the sheet 512 to be separated, is transported along theblocking face 514. (FIG. 62).

As soon as the transporter face 510 passes over the step 516 whichseparates the blocking face from the support, the entire pile isdisplaced further downwards by the height of this step, the sheet 508positioning the lowermost sheet 512 behind the step. The step 516 has aheight exceeding the thickness of one sheet and less than the thicknessof two sheets. The best compromise it to make the sum of the heights ofthe step 516 and the transporter face 510 equal to the thickness of twosheets. The bottom surface 518 of the shoe which extends parallel to thesupport ensures that the sheet 512 is positioned flat on the support andthat the sheet 508 is reliably presented to the transporter face 510.

As shown in FIG. 64, the lower edges of the shoe lying one behind theother are offset in relation to the small roller such that the edgecannot ride on the sheet 508 despite a maximum inclined position of therail (about 7°) and cannot lift the roller away from the sheet 512,which would impair the clamping function thereof.

A further modification of this principle is illustrated in FIG. 65. Thestep 600 between the blocking face 604 and support 602 has a height thatis somewhat greater than the thickness of two sheets. The shoe again hasits own transporter face 606 for the lowermost sheet 608, which restsnot on the blocking face 604, but hangs down between the two ribscarrying the blocking faces, so that only the lowermost sheet 610remains positioned on the support 602 while the sheet 608 is takenalong. This construction has the advantage that all the sheet edges arepressed as far as the step 600 in the direction of the housing base andboth lowermost sheets are reliably positioned behind the step 600. Forthis reason the transporter face is set back with respect to the endedge of the inclined face since the displacement of the sheets 608, 610to behind the step 600 requires a certain stroke. The horizontal roofing612 calibrates the aperture and holds sheet 610 reliably on the support.

Since both sheets 608, 610 are braked, not only is sheet 610 held firmlyat its other end by means of a hook but also sheet 608 too, which,however, must be released again. For this reason only a braking hook andnot an arresting hook is suitable, for example as shown in FIG. 1 at126.

The construction shown in FIG. 66, in which the transporter face for thesecond lowermost sheet directly adjoins the inclined face, is lesssuitable, for the reasons discussed above, but may function if thechanger is operated relatively slowly.

I claim:
 1. A device for cyclic rearrangement of a pile of substantiallyrectangular sheets, comprising:a first frame part and a second framepart, one of said frame parts having a viewing window therein, saidsecond frame part being reciprocable relative to said first frame partin a reciprocation direction between an inner end position and an outerend position over a stroke limited by stop means, means for removing asheet from a first end of an inserted pile when said second frame partis displaced from said inner end position to said outer end position andfor adding said removed sheet to a second end of said pile when saidsecond frame part is displaced from said outer end position back to saidinner end position, said removing and adding means including transfermeans for displacing said removed sheet from said first pile end towardsaid second pile end, and spring-biased pressing means for pressing saidpile towards said viewing window when said second frame part is in saidinner end position, said pressing means including two rail elements madeof plastics material, said rail elements being arranged symmetricallywith respect to a central plane of symmetry extending in saidreciprocation direction, each rail element having a length substantiallyequal to said stroke, each rail element being supported by a leafspring, each leaf spring having a first end fastened to said first framepart and a second end supported by said first frame part, each leafspring being bowed between said first and second ends towards saidviewing window and connected approximately midways between said firstand second ends to said rail element allocated thereto, and a spacebeing provided between said rail elements for accommodation of saidtransfer means.
 2. A device for cyclic rearrangement of a pile ofsubstantially rectangular sheets, comprising:a first frame part and asecond frame part, one of said frame parts having a viewing windowtherein, said second frame part being reciprocable relative to saidfirst frame part in a reciprocation direction between an inner endposition and an outer end position over a stroke limited by stop means,means for removing a sheet from a first end of an inserted pile whensaid second frame part is displaced from said inner end position to saidouter end position and for adding said removed sheet to a second end ofsaid pile when said second frame part is displaced from said outer endposition back to said inner end position, and spring-biased pressingmeans for pressing said pile towards said viewing window when saidsecond frame part is in said inner end position, said pressing meansincluding at least one rail element extending in said reciprocationdirection and having a length substantially equal to said stroke, saidat least one rail element being supported on a spring, wherein saidfirst frame part is a housing having said viewing window and, oppositethereto, a housing bottom, and said second frame part is a slider membertelescopically reciprocable through a housing opening parallel to saidviewing window, said at least one rail element being provided adjacentsaid housing opening with means for blocking the insertion of sheetsbetween said at least one rail element and said housing bottom.
 3. Adevice according to claim 2 wherein said blocking means is integrallymoulded on a rail end adjacent said opening.
 4. A device according toclaim 2 wherein said blocking means comprises a projection directedtowards said housing bottom.
 5. A device according to claim 4 whereinsaid slider member has a transverse strut serving as a separator andrunning over said at least one rail element and in said outer endposition resting on said rail element close to an end adjacent saidopening thereof, in this position said projection reaching almost tosaid housing bottom.
 6. A device according to claim 2 wherein saidblocking means is movably joined to said rail element.
 7. A deviceaccording to claim 6 wherein said blocking means comprises a flap hingedto a rail end adjacent said opening, a free flap end being guided onsaid housing.
 8. A device according to claim 6 wherein said free flapend is guided in a sliding manner on said housing bottom in direction ofreciprocation of said slider member.
 9. A device according to claim 2wherein said slider member has surface portions opposite said viewingwindow and supporting said pile of sheets, wherein said blocking meansdefines a level parallel to said viewing window which is further awayfrom said window than said pile-supporting surfaces of said slidermember.
 10. A device according to claim 4 wherein said projection isinclined towards said housing opening and housing bottom.
 11. A deviceaccording to claim 2 wherein blocking elements for guiding sheet edgesover said blocking means are integrally moulded on said housing bottom.12. A device for cyclic arrangement of a pile of substantiallyrectangular sheets, comprising:a first frame part and a second framepart, one of said frame parts having a viewing window therein, saidsecond frame part being reciprocable relative to said first frame partin a reciprocation direction between an inner end position and an outerend position over a stroke limited by stop means, means for removing asheet from a first end of an inserted pile when said second frame partis displaced from said inner end position to said outer end position andfor adding said removed sheet to a second end of said pile when saidsecond frame part is displaced from outer end position back to saidinner end position, and spring-biased pressing means for pressing saidpile towards said viewing window when said second frame part is in saidinner end position, said pressing means including at least one railelement extending in said reciprocation direction and having a lengthsubstantially equal to said stroke, said at least one rail element beingsupported on a spring, wherein said first frame part is a housing havingsaid viewing window and, opposite thereto, a housing bottom, and saidsecond frame part is a slider member telescopically reciprocable througha housing opening parallel to said viewing window, said at least onerail element having a first end adjacent said housing opening and asecond end remote from said housing opening, said slider member having apile transporter passing over said rail element upon slider memberreciprocation and in said outer end position presses said first railelement end away from said viewing window, said housing having means fordepressing, upon each slider reciprocation, said second rail element endaway from said viewing window whereby, each time said slider is in saidouter end position, said rail element assumes a position substantiallyparallel to said viewing window, said depressing means beingrespectively activated and deactivated in response to each sliderreciprocation.
 13. A device according to claim 12 wherein saiddepressing means enters into operative engagement with said second railelement end.
 14. A device according to claim 13 wherein said depressingmeans comprises anchoring hooks integrally moulded on said housingbeneath which hooks said second rail element end is displaceable as saidslider member is displaced towards said outer end position, and fromwhich said second rail element end is releasable as said slider memberis displaced towards said inner end position.
 15. A device according toclaim 12 wherein said depressing means defines a level of a side of saidrail element facing towards said viewing window, said level lyingbeneath said pile transporter.
 16. A device according to claim 14wherein said pile of sheets is supported with respect to said viewingwindow on faces of said slider member that are parallel to said viewingwindow and wherein a window-facing side of said rail element liesapproximately flush with said faces when said slider member is in saidouter end position.
 17. A device according to claim 12 wherein said railelement is displaceable in engagement with said anchoring hooks byperforming a tilting motion about an end of its supporting spring upondisplacement of said slider member from said inner end position towardssaid outer end position.
 18. A device according to claim 13 whereinanchoring hooks are arranged displaceably on said housing, said hooksbeing displaced in engagement with said rail element end as the slidermember is displaced from said inner end position towards said outer endposition, and said hooks being displaced into a disengaging position assaid slider member is displaced from said outer end position towardssaid inner end position.
 19. A device according to claim 18 wherein saidanchoring hooks are displaceable towards said housing opening.
 20. Adevice according to claim 18 wherein said anchoring hooks arespring-biased into their engaging position.
 21. A device according toclaim 20 wherein said anchoring hooks are part of a resilient member.22. A device according to claim 18 wherein said anchoring hooks arepivotably movable.
 23. A device according to claim 14 or 17, whereinsaid second rail element end is first depressed to a level below saidanchoring hooks and then raised until it enters into engagement withsaid hooks.
 24. A device for cyclic rearrangement of a pile ofsubstantially rectangular sheets, comprising:a first frame part and asecond frame part, one of said frame parts having a viewing windowtherein, said second frame part being reciprocable relative to saidfirst frame part in a reciprocation direction between an inner endposition and an outer end position over a stroke limited by stop means,means for removing a sheet from a first end of an inserted pile whensaid second frame part is displaced from said inner end position to saidouter end position and for adding said removed sheet to a second end ofsaid pile when said second frame part is displaced from said outer endposition back to said inner end position, and spring-biased pressingmeans for pressing said pile towards said viewing window when saidsecond frame part is in said inner end position, said pressing meansincluding at least one rail element extending in said reciprocationdirection and having a length substantially equal to said stroke, saidat least one rail element being supported on a spring, wherein saidfirst frame part is a housing having said viewing window and, oppositethereto, a housing bottom, and said second frame part is a slider membertelescopically reciprocable through a housing opening parallel to saidviewing window, said at least one rail element having a first endadjacent said housing opening and a second end remote from said housingopening, said slider member having a pile transporter passing over saidrail element upon slider member reciprocation, wherein said at least onerail element has means for engaging a transverse edge of saidto-be-removed sheet adjacent said first rail element edge so as toretain said to-be-removed sheet while remaining sheets of said pile arepassed across said engaging means by said pile transporter.
 25. A deviceaccording to claim 24 wherein said engaging means comprises at least oneprojection which projects beyond a side of said rail element facingtoward said pile of sheets.
 26. A device according to claim 25 includinga pair of projections arranged symmetrically on said at least one railelement.
 27. A device according to claim 25 wherein said projection hasan inclined face facing towards the pile of sheets.
 28. A deviceaccording to claim 25 wherein said projection has an inclined facefacing away from the pile of sheets.
 29. A device according to claim 25wherein said projection protrudes beyond said rail element side by anamount exceeding a thickness of one sheet.
 30. A device according toclaim 25 wherein said projection is integrally formed with said railelement.
 31. A device according to claim 25 wherein said piletransporter includes a transverse strut overrunning said projection assaid slider member is displaced from said inner end position towardssaid outer end position, said strut having apertures for passage of saidprojection.
 32. A device according to claim 25 wherein said projectioncomprises a hook extending substantially at right angles to the plane ofthe to-be-removed sheet, the height of said hook being less than athickness of one sheet.
 33. A device according to claim 32 wherein saidhook is located at an end of a plateau substantially parallel to theplane of the to-be-removed sheet.
 34. A device according to claim 32wherein a sloping ramp is provided in front of said hook.
 35. A deviceaccording to claim 34 wherein said ramp is provided on a hook-side halfof said rail element.
 36. A device according to claim 34 wherein saidrail element carries a retentive covering strip which lies on a supportramp parallel with said sloping ramp.
 37. A device according to claim 25wherein on both sides of a retentive strip applied to said rail elementthere is provided one projection spaced from said strip.
 38. A deviceaccording to claim 24 in which on a housing wall facing said railelement there are provided sheet holding-down members in overlappingrelation with said engaging means.
 39. A device according to claim 24wherein said rail element projects beyond said engaging means.
 40. Adevice for cyclic rearrangement of a pile of substantially rectangularsheets, comprising:a first frame part and a second frame part, one ofsaid frame parts having a viewing window therein, said second frame partbeing reciprocable relative to said first frame part in a reciprocationdirection between an inner end position and an outer end position over astroke limited by stop means, means for removing a sheet from a firstend of an inserted pile when said second frame part is displaced fromsaid inner end position to said outer end position and for adding saidremoved sheet to a second end of said pile when said second frame partis displaced from said outer end position back to said inner endposition, and spring-biased pressing means for pressing said piletowards said viewing window when said second frame part is in said innerend position, said pressing means including at least one rail elementextending in said reciprocation direction, wherein said at least onerail element is provided with means for retaining said to-be-removedsheet, said retaining means including a strip frictionally engaging saidto-be-removed sheet, said at least one rail element being furtherprovided with spacer elements next to said strip, and second frame parthaving means for depressing said to-be-removed sheet in engagement withsaid strip when said second frame part is displaced from said inner endposition towards said outer end position, and remaining sheets of saidpile riding on said spacer elements out of engagement with said stripwhen said second frame part is displaced from said outer end positiontowards said inner end position.
 41. A device according to claim 40wherein said strip is formed by a retentive covering strip.
 42. A deviceaccording to claim 40 wherein said depressing element is provided on atransporter for said remaining sheets.
 43. A device according to claim42 wherein said depressing element is a rotatable roller.
 44. A deviceaccording to claim 40 wherein said depressing element is supportedresiliently on a transporter for remaining sheets of said pile.
 45. Adevice according to claim 40 wherein said spacer elements compriseupright ribs projecting away from said rail element.
 46. A deviceaccording to claim 43 wherein said roller is mounted in a shoe which isguided in a sliding manner on said transporter.
 47. A device accordingto claim 46 wherein said shoe has an edge remote from said viewingwindow on a level that is further removed from the viewing window than alevel defined by said spacer elements where said to-be-removed sheet isclamped between said roller and said strip.
 48. A device according toclaim 47 wherein spacer ribs are provided on both sides of said shoe.49. A device according to claim 40 wherein said spacer elements extendfor a substantial part of the length of said rail element.
 50. A deviceaccording to claim 40 or 49 wherein said spacer elements are located atother than a rail element end adjacent a transporter for remainingsheets of said pile when said second frame part is in said inner endposition.
 51. A device according to claim 41 wherein said rail elementis injection-moulded from plastic material, said retentive coveringstrip is shorter than said rail element and is cut off obliquely at itsends, and wherein said rail element has a tolerance-compensatingprojection close to said oblique end of said covering strip, saidprojection having a height that increases transversely to said rail froma minimum, corresponding to a relatively thin covering strip, to amaximum corresponding to a relatively thick covering strip.
 52. A devicefor cyclic rearrangement of a pile of substantially rectangular sheets,comprising:a first frame part and a second frame part, one of said frameparts having a viewing window therein, said second frame part beingreciprocable relative to said first frame part in a reciprocationdirection between an inner end position and an outer end position over astroke limited by stop means, means for removing a sheet from a firstend of an inserted pile when said second frame part is displaced fromsaid inner end position to said outer end position and for adding saidremoved sheet to a second end of said pile when said second frame partis displaced from said outer end position back to said inner endposition, and spring-biased pressing means for pressing said piletowards said viewing window when said second frame part is in said innerend position, said pressing means including at least one rail elementextending in said reciprocation direction, wherein said at least onerail element is provided with means for retaining said to-be-removedsheet, and said second frame part is provided with means fortransporting remaining sheets of said pile, said retaining means forsaid to-be-removed sheet including a gripping element displaceablerelative to said to-be-removed sheet so as to engage a side thereoffacing said remaining sheets and to press it against said at least onerail element, the device further comprising means for controllingdisplacement of said gripping element in response to reciprocation ofsaid second frame part.
 53. A device according to claim 52 wherein saidgripping element is displaceable, in a direction in which said railelement extends, between a pressing position and a releasing position.54. A device according to claim 52 wherein said gripping element isdisplaceable by collision with said second frame part.
 55. A deviceaccording to claim 52 wherein said gripping element has resilientlydeflectable arms.
 56. A device according to claim 52 wherein saidgripping element is controlled by collision with remaining sheets ofsaid pile.
 57. A device according to claim 52 wherein said grippingelement is separable from said to-be-removed sheet when said secondframe part is displaced towards said inner end position.
 58. A deviceaccording to claim 52 wherein said gripping element is spring-biasedinto one of two end positions.
 59. A device according to claim 52wherein said gripping element is displaced into a pressing position oncesaid transporting means has passed over a transverse edge of theto-be-removed sheet.
 60. A device according to claim 52 wherein saidgripping element engages an individual sheet end over which saidtransporting means passes last.
 61. A device according to claim 60comprising means for lifting said remaining sheets so as to allow adisplacement of said gripping element in engagement with saidto-be-removed sheet.
 62. A device for cyclic rearrangement of a pile ofsubstantially rectangular sheets, comprising:a first frame part and asecond frame part, one of said frame parts having a viewing windowtherein, said second frame part being reciprocable relative to saidfirst frame part in a reciprocation direction between an inner endposition and an outer end position over a stroke limited by stop means,means for removing an individual sheet from a first end of an insertedpile when said second frame part is displaced from said inner endposition to said outer end position and for adding said individualremoved sheet to a second end of said pile when said second frame partis displaced from said outer end position back to said inner endposition, a first retaining element for said individual sheet in saidfirst frame part, and a second retaining element for remaining sheets ofsaid pile in said second frame part, wherein: said first retainingelement comprises a stop element engaged by a transverse edge of saidindividual sheet end comprising further a gripping element adapted to bepositioned on a side of said individual sheet facing towards saidremaining sheets and projecting between said individual sheet and saidremaining sheets.
 63. A device according to claim 62 wherein said firstretaining element is arranged on a rail element which presses said piletowards said viewing window when said second frame part is in said innerend position.
 64. A device according to claim 62 wherein said firstretaining element can be switched between a retaining position and areleasing position through running over of said second frame part.
 65. Adevice according to claim 62, 63 or 64 wherein said first grippingelement holds said individual sheet until said second frame part hasreached its outer end position.
 66. A device according to claim 62including means for lifting said remaining sheets so as to allowintroduction of said gripping member between said individual sheet andsaid remaining sheets.
 67. A device for cyclic rearrangement of a pileof substantially rectangular sheets having substantially identicalthickness, comprising:a first frame part and a second frame part, one ofsaid frame parts, having a viewing window therein, said second framepart being reciprocable relative to said first frame part in areciprocation direction between an inner end position and an outer endposition, means for removing an individual sheet from a first end of aninserted pile when said second frame part is displaced from said innerend position to said outer end position and for adding said removedsheet to a second end of said pile when said second frame part isdisplaced from said outer end position back to said inner end position,spring-biased pressing means for pressing said pile towards said viewingwindow when said second frame part is in said inner end position, saidpressing means including at least one rail element extending in saidreciprocation direction, said at least one rail element being supportedon a spring, wherein said pressing means is mounted in said first framepart, and a first separating element be stationarily provided in saidfirst frame part said first separating element cooperating with a secondseparating element provided on said second frame part to define uponreciprocation start a passage gap for separation of said individualsheet from remaining sheets of said pile, said second separating elementupon further displacement of said second frame part running onto saidindividual sheet supported by said at least one rail element so as toform in cooperation with said pressing means a barrier which blockspassage of further ones of said remaining sheets.
 68. A device accordingto claim 67 wherein said second frame part has a transverse strut fortransporting said remaining sheets, said strut carrying said secondseparating element.
 69. A device according to claim 67 wherein saidfirst and second separating elements are biased resiliently towards oneanother at least while reciprocation begins.
 70. A device according toclaim 69 wherein displaceable shoes are arranged on said transversestrut and are supported against said strut by springs.
 71. A deviceaccording to claim 68 wherein said first separating element comprises astep of a height that is greater than the thickness of one sheet andless than the thickness of two sheets.
 72. A device according to claim71 wherein adjoining said step in a direction opposing a withdrawaldisplacement of said second frame part there is a blocking face on whichsaid second separating element can be positioned.
 73. A device accordingto claim 72 wherein adjoining said step in said withdrawal displacementdirection there is a positioning face for said individual sheet.
 74. Adevice according to claim 67 wherein at least one of said first andsecond separating elements is provided with tapering run-on faces.
 75. Adevice according to claim 67 wherein said first separating element isprovided on ribs which extend in said reciprocation direction.
 76. Adevice according to claim 75 comprising at least one pair of congruentribs.
 77. A device according to claim 67 wherein cooperating first andsecond separating elements are provided on both sides of a plane ofsymmetry extending in said reciprocation direction.
 78. A deviceaccording to claim 70 wherein in said inner end position of said secondframe part said shoe cooperates with an inclined face thereby lockingsaid second frame part with respect to said first frame part.
 79. Adevice according to claim 67 wherein said second separating elementincludes a small roller which protrudes beyond an operative edge of saidsecond separating element by less than the thickness of one sheet.
 80. Adevice according to claim 79 wherein said first separating element has arecess such that said small roller is relieved of stress when saidsecond frame part is in said inner end position.
 81. A device accordingto claim 67 wherein in said reciprocation direction said rail element isaligned with said first and second separating elements.
 82. A deviceaccording to claim 81 wherein said rail element has an end that engagescomb-like with said first separating element.
 83. A device according toclaim 67 wherein said second separating element is disposed on atransversely extending separator strut of said second frame part, saidstrut having surface portions defining an acute angle with a principalplane of the pile, which surface portions, as said second frame part isdisplaced from said inner towards said outer position, run onto an endof said rail element and displace said end towards said first separatingelement.
 84. A device according to claim 83 wherein said rail elementend is displaceable to such an extent that said individual sheet isdeposited on a positioning surface.
 85. A device according to claim 84wherein said rail element end is displaceable to such an extent thatsaid second separating element is able to run onto the positionedindividual sheet.
 86. A device according to claim 83 wherein said railelement end has thickened control prongs onto which said strut runs. 87.A device according to claim 86 wherein said rail element end has acentral prong onto which a small roller provided on said secondseparating element runs.
 88. A device according to claim 86 wherein saidprongs define a first level for said rail element end from which saidrail element end is further displaced by an on-running small roller. 89.A device according to claim 87 wherein in continuation of said centralprong there is applied to said rail element a retentive covering onwhich said small roller is able to roll.
 90. A device according to claim67 wherein means for depressing said rail element is provided adjacentsaid first separating element.
 91. A device according to claim 67wherein said rail element is supported on a leaf spring having an endadjacent said first separating element.
 92. A device according to claim67 wherein said first separating element is integrally moulded with abottom of said first frame part opposite said viewing window.
 93. Adevice according to claim 1 wherein said rail elements engage saidsheets adjacent their edges lying parallel to displacement direction ofsaid second frame part.
 94. A device according to claim 1 wherein eachrail element is supported on a metal spring.
 95. A device according toclaim 1 wherein said second leaf spring end is laterally supported. 96.A device according to claim 95 wherein said second leaf spring end isguided in a groove opposite said viewing window and extending in saidreciprocation direction.
 97. A device according to claim 1 wherein saidfirst leaf spring end is placed on a pin provided on the first framepart.
 98. A device according to claim 1 wherein each rail element hasreinforcing ribs on its side remote from the viewing window.
 99. Adevice according to claim 1 wherein each rail element is of symmetricalconstruction with respect to its longitudinal central plane.
 100. Adevice according to claim 1 wherein said second frame part has a griprecess which projects into a free space of said first frame part.
 101. Adevice according to claim 100 wherein said grip recess is central withrespect to a central plane of symmetry that extends in saidreciprocation direction.
 102. A device according to claim 101 whereinbetween said grip recess and each side wall of said second frame partthere is provided a free space.
 103. A device according to claim 102wherein one rail element is provided on each side of said central planeand projects with one end into one of said free spaces.
 104. A deviceaccording to claim 102 wherein said free spaces extend for an entireheight of the second frame part.
 105. A device according to claim 1including auxiliary springs which form said transfer means.
 106. Adevice according to claim 105 wherein said auxiliary springs arearranged in pairs and symmetrically with respect to said reciprocationdirection.
 107. A device according to claim 105 wherein said auxiliarysprings are arranged laterally next to said rail elements.
 108. A deviceaccording to claim 107 wherein said auxiliary springs are arrangedbetween said pair of rail elements.
 109. A device according to claim 67wherein said second frame part has pile-supporting faces that are setwith respect to said second separating element in direction ofdisplacement of said second frame part from said inner end portiontowards said outer end position.
 110. A device according to claim 109wherein ends of said pile-supporting faces are approximately flush witha part of said second separating element that projects outwardsfurthest.
 111. A device according to claim 67 wherein said shield stepis defined by said positioning member and a blocking face.
 112. A deviceaccording to claim 111 wherein said transport member faces include aninclined face forming an acute angle with said plane and transmitting aforce onto said sheets towards said positioning member, said inclinedface terminating flush with said blocking face.
 113. A device accordingto claim 111 wherein said transport member faces include an inclinedface forming an acute angle with said plane and transmitting a forceonto said sheets towards said positioning member, said inclined facebeing spaced from said blocking face by less than said thickness.
 114. Adevice according to claim 113 or 112 wherein adjoining said inclinedface, said step portion extends towards said positioning member.
 115. Adevice according to claim 111 wherein said end edge defines a levelbetween that of said blocking face and that of said support plane. 116.A device according to claim 115 wherein said blocking face is defined bytwo congruent spaced ribs and said step portion is located between saidribs.
 117. A device according to claim 116 wherein said transport memberand said positioning member are biased resiliently towards one another.118. A device according to claim 117 wherein said transport membercomprises a spring-loaded shoe which exhibits at least said stepportion.
 119. A device according to claim 116 wherein said guiding meanscomprises control faces along which the transverse edge of saidindividual sheet is displaced during separation past said end edge in adirection transverse to said plane.
 120. A device according to claim 119wherein said control faces are offset with respect to said step portionin said transport member displacement direction.
 121. A device accordingto claim 116 wherein said guide means is structurally combined with saidpositioning member.